This invention relates to a flexible shaft liner assembly for holding a flexible shaft rotatably in its inside and a torque transmitting shaft for transmitting a torque of an engine etc. by the flexible shaft to a rotating body such as a cutter blade etc.
Generally, the torque transmitting shaft is constructed in such a way that a flexible shaft liner is inserted in an external tube and the flexible shaft is inserted in the flexible shaft liner. In the torque transmitting shaft using the flexible shaft, however, occurrence of vibration caused by rotation of the flexible shaft has become serious trouble. In a mowing machine, for example, the vibration has reached hands operating the machine to make the operation impossible. For this reason, torque transmitting shafts illustrated in FIG. 15 and FIG. 16 have been proposed in order to solve such the trouble. FIG. 15 and FIG. 16 are partially exploded oblique views of conventional torque transmitting shafts respectively.
In the torque transmitting shaft of FIG. 15, plural tubular thick vibration-proof rubbers 18 fitted onto a tubular flexible shaft liner 17 are fitted in an external tube 11, so that the liner is held by the external tube 11. The vibration-proof rubber 18 is a component for preventing the vibration caused by rotation of the flexible shaft 13 from transmitting to the external tube 11 through the flexible shaft liner 17. Therefore, the vibration-proof rubbers 18 are installed at positions where vibration-proof effect is obtained most efficiently in a longitudinal direction of the flexible shaft liner 17. The vibration-proof rubbers 18 are secured to the flexible shaft liner 17 by bonding agent coated on inside surfaces of these rubbers.
However, the example of FIG. 15 has included such problems as follows. The flexible shaft liner 17 is generally made of 6,6-nylon, and this 6,6-nylon refuses the bonding agent, so that the vibration-proof rubber 18 can not be secured to the flexible shaft liner 17 firmly. For this reason, when the flexible shaft liner 17 fitted with the vibration-proof rubber 18 is inserted in the external tube 11, the vibration-proof rubbers 18 get out of respective previously specified positions, so that a desired vibration-proof effect can not be obtained. In addition, a bonding work of the vibration-proof rubber 18 has been troublesome and a workability of manufacture has been worse.
In the torque transmitting shaft of FIG. 16, a flexible shaft liner 19 is directly installed in the external tube 11 through plural projecting portions 191 formed on an outer surface of the liner.
However, the example of FIG. 16 has included such problems as follows. Since the flexible shaft liner 19 is hard because it is made of 6,6-nylon, almost all vibrations of the flexible shaft 13 are transmitted as they are to the external tube 11 through the flexible shaft liner 19, so that the vibration-proof effect has been nearly lost. In addition, it is impossible to fabricate the flexible shaft liner 19 just to specified dimensions, so that the flexible shaft liner 19 is hard to be inserted in the external tube 11 when its overall dimensions are large and the flexible shaft liner 19 revolves together with the flexible shaft 13 when its overall dimensions are small. Therefore, a torque transmitting effect has become extremely worse.